The present invention relates to an operation device having a function for illuminating an operation portion.
A typical operation device arranged in, for example, a passenger compartment of a vehicle illuminates an operation portion during the nighttime. This enables the position of the operation portion to be identified.
Referring to FIG. 1, an operation device 51 of the prior art includes an ornamental panel 53 and a switch assembly 54, which is arranged at the rear side of the ornamental panel 53. The ornamental panel 53 includes a plurality of operation portions 52. A plurality of illumination windows 57 are respectively arranged adjacent to the plurality of operation portions 52. The switch assembly 54 includes a circuit board 55 and an elastomeric sheet 56 covering the circuit board 55. The circuit board 55 includes switches respectively located at positions corresponding to the operation portions 52. The elastomeric sheet 56 is transparent and planar. The circuit board 55 also includes a plurality of light sources 58, such as top-view type LEDs, respectively located at positions corresponding to the illumination windows 57.
Each light source 58 emits light through and out of the corresponding illumination window 57. The light illuminates the operation portion 52. This enables recognition of the operation portion 52 during the nighttime.
However, the operation device 51 of the prior art requires each operation portion 52 to be provided with the light source 58. This increases the components mounted on the circuit board 55, enlarges the circuit board 55, and imposes restrictions on the component layout of the circuit board 55. Further, the light sources 58 may have different qualities. In such a case, the brightness and color of the light may differ between operation portions 52.
Japanese Laid-Open Patent Publication No. 8-194219 describes an illumination device that uses a light guide.
FIG. 2 schematically shows the illumination device of the above publication. As shown in FIG. 2, the illumination device 61 includes a light guide 62, which is planar and made of an acrylic resin. A light source 63, such as a side view type LED, is arranged beside the light guide 62. The light guide 62 includes a plurality of projections 64 formed on the opposite side of a light emitting surface 62a. The light source 63 emits light that enters one end face of the light guide 62. The projections 64 diffuse the light from the light source 63 to illuminate the light emitting surface 62a. In this manner, the illumination device 61 can illuminate a plurality of illumination windows, which are arranged at locations corresponding to the light emitting surface 62a, with a single light source 63.
Application of the illumination device 61 of FIG. 2 to the operation device 51 of FIG. 1 would reduce the components that are mounted in the circuit board 55 and increase the freedom for the component layout of the circuit board 55. In this case, for example as shown in FIG. 3, the light guide 62 is arranged between the operation portions 52 and the elastomeric sheet 56. The light source 63, which is a side-view type LED, is arranged beside the light guide 62. The light of the light source 63 entering the end face of the light guide 62 is diffused and reflected in the light guide 62, and the projections 64 reflect the light toward the illumination windows 57. The light is emitted out of the illumination windows 57. This illuminates the illumination windows 57. Thus, the operation device 51 of FIG. 3 illuminates a plurality of the illumination windows 57 with a single light source. This reduces the components mounted on the circuit board 55 and increases the component layout freedom.
However, the operation device 51 of FIG. 3 includes a switch contact 52a for each operation portion 52. Further, the elastomeric sheet 56 also includes switch contacts 56a that correspond to the switch contacts 52a of the operation portions 52. To prevent the light guide 62 from interfering with the switch contacts 52a and 56a, openings 62b must be formed in the light guide 62. However, the openings 62b located between the light source 63 and the illumination windows 57 would result in the amount of light guided to the illumination windows 57 being insufficient. As a result, the brightness of the illumination windows 57 may be insufficient. Further, the brightness may differ between illumination windows 57.
Additionally, the light guide 62 may be displaced with respect to the light source 63. This would result in an insufficient amount of light entering the light guide 62 from the light source 63.
Further, space for a circuit board 65, which is used to operate the light source 63, must be provided beside the light guide 62. This enlarges the operation device 51 in the planar direction (lateral direction in FIG. 3).
In this manner, the operation device 51 of FIG. 3, which applies the teaching of the above publication still has various problems and requires improvements.